DeviceIoControlAsync incorrent pointer offset of input/output buffer about vanara

[dahall]

Does this look correct?

private static unsafe IAsyncResult BeginDeviceIoControl<TIn, TOut>(HFILE hDevice, uint dwIoControlCode, byte[] buffer, AsyncCallback userCallback, object userState) where TIn : struct where TOut : struct
{
   var ar = OverlappedAsync.SetupOverlappedFunction(hDevice, userCallback, buffer);
   var prefix = Marshal.SizeOf(typeof(int)) * 2;
   var inSz = Marshal.SizeOf(typeof(TIn));
   fixed (byte* pIn = &buffer[prefix], pOut = &buffer[prefix + inSz])
   {
      var ret = DeviceIoControl(hDevice, dwIoControlCode, pIn, (uint)inSz, pOut, (uint)Marshal.SizeOf(typeof(TOut)), out var bRet, ar.Overlapped);
      return OverlappedAsync.EvaluateOverlappedFunction(ar, ret);
   }
}

[GF-Huang]

it's ok, could you update it to nuget as soon as possible ? thank you.

[dahall]

I'm in the process of testing major changes to the libraries, but expect that testing to take the next 2 weeks. I will release version 2.0 at that time and include this fix.

[GF-Huang]

ok, thanks.

[GF-Huang]

Hey, I find some other troubles:

1.

when calling Task<TOut?> DeviceIoControlAsync<TOut>(SafeFileHandle hDev, uint ioControlCode),
it assume input buffer is (int?) and pass null into :

It will never be zero.

2.

Does this look correct?

private static unsafe IAsyncResult BeginDeviceIoControl<TIn, TOut>(HFILE hDevice, uint dwIoControlCode, byte[] buffer, AsyncCallback userCallback, object userState) where TIn : struct where TOut : struct
{
   var ar = OverlappedAsync.SetupOverlappedFunction(hDevice, userCallback, buffer);
   var prefix = Marshal.SizeOf(typeof(int)) * 2;
   var inSz = Marshal.SizeOf(typeof(TIn));
   fixed (byte* pIn = &buffer[prefix], pOut = &buffer[prefix + inSz])
   {
      var ret = DeviceIoControl(hDevice, dwIoControlCode, pIn, (uint)inSz, pOut, (uint)Marshal.SizeOf(typeof(TOut)), out var bRet, ar.Overlapped);
      return OverlappedAsync.EvaluateOverlappedFunction(ar, ret);
   }
}

I had test this code, if I call DeviceIoControlAsync<TIn>(SafeFileHandle hDev, uint ioControlCode, TIn inVal),
pOut = &buffer[prefix + inSz] will cause index out of range exception, because output buffer is null from here:

so prefix + inSz is equal to buffer.Length (it should be less than or equal to buffer.Length - 1)

My solution for both troubles:

private static unsafe IAsyncResult BeginDeviceIoControl(SafeFileHandle hDevice, uint dwIoControlCode, byte[] buffer, AsyncCallback userCallback, object userState) where TIn : struct where TOut : struct
{
    var ar = OverlappedAsync.SetupOverlappedFunction(hDevice, userCallback, buffer);
    var prefix = Marshal.SizeOf(typeof(int)) * 2;
    var inSz = BitConverter.ToInt32(buffer, 0);
    var outSz = BitConverter.ToInt32(buffer, sizeof(int));

    fixed (byte* pIn = &buffer[prefix], pOut = &buffer[outSz == 0 ? 0 : prefix + inSz])
    {
        var ret = DeviceIoControl(hDevice, dwIoControlCode, pIn, (uint)inSz, pOut, (uint)outSz, out uint bRet, ar.Overlapped);
        return OverlappedAsync.EvaluateOverlappedFunction(ar, ret);
    }
}

because outSz is zero when POut is null, so will not effect origin buffer.

[dahall]

Thank you for all your work on this! I will update the code with your fixes and post it later today.

[dahall]

Fixed in 2.0 release today